1. Field of the Invention The present invention relates to clamps, and more particularly, to a clamp with ratchet device.
2. Description of the Related Art
A clamp usually has a configuration including a fixed part and an active part, wherein the active part is allowed to be moved toward or away from the fixed part, thereby clamping a target object and achieving different operational demands.
U.S. Pat. No. 8,025,275 discloses a single hand operated ratchet clamp, comprising a slide rail, a sliding arm, a fixed arm, a lever element, and a pressure plate. When clamping an object, user grips the slide rail with one hand and uses the lever element to move the sliding arm toward the fixed arm with the other hand. When the target object is to be clamped, through deflecting the lever element, the pressure plate rapidly pushes and presses the target object, achieving a one-hand operation. However, when the pressure plate pushes and presses the target object, the user is unable to make the pressure plate further exert additional pressure upon the target object through the lever element, failing to meet the requirement of tightly and stably clamping the target object.
U.S. Pat. No. 8,025,279 also discloses a ratcheting C-clamp, comprising a main body, a threaded rod, an actuator, a ratchet mechanism, and a gear assembly. The thread rod is movably connected to the main body, and the actuator is mechanically connected to the thread rod through the ratchet mechanism, whereby the thread rod is able to axially move toward or away from a target object. Furthermore, the ratchet mechanism is further connected to the thread rod through the gear assembly which comprises external teeth that couple to external threads on the rod. Therefore, with the actuator as a handgrip, user is able to make the thread rod move toward or away from the target object by operating the handgrip with only one hand. However, the rod needs to be rotated by the lever on one end of the rod, whereby the clamping force of the C-clamp is exerted upon the target object, facilitating the mechanical operation of the clamp and stably clamping the target object on the main body. However, in a narrow operational environment, exerting the clamping force by use of the lever is inconvenient, and the clamping force exerted might be insufficient. Also, an exposed spring is disposed between the handle and the main body; as a result, other objects may be accidentally hooked, causing the handle to be malfunctioned.